turtle.select(1)
local function forward(x)
  for i = 1, x do
    turtle.forward()
    turtle.digDown()
    turtle.placeDown()
  end
end
forward(10) -- move forward 10 blocks
turtle.turnLeft()
forward(1)
turtle.turnLeft()
forward(9)
turtle.turnRight()
forward(1)
turtle.turnRight()
forward(9)
turtle.turnLeft()
forward(1)
turtle.turnLeft()
forward(10)
turtle.turnLeft()
forward(3)
turtle.turnLeft()